The present invention relates to an air conditioner using a heat pump, and more particularly to a heat pump air conditioner which has good starting characteristics for heating.
The prior art will be explained by referring to FIG. 1. In FIG. 1, designated at reference numeral 1 is a compressor, 2 a four-way valve, 3 an outdoor heat exchanger, 4 an indoor heat exchanger, 5 an expansion valve (or decompression device), 6 an electric motor to drive the compressor, 7 an inverter to change the r.p.m. of the electric motor 6, 8 a blower for the outdoor heat exchanger (including an electric motor for the blower), 9 a blower for the indoor heat exchanger (including an electric motor for the blower), 11 a sensor for detecting the temperature of air flowing into the indoor heat exchanger (i.e., room temperature), 12 a setting unit to set the desired temperature, 13 a temperature comparator to compare the temperature detected by 11 and preset by 12, and 17 is a controller to send an instruction to the inverter 7 based on the results from the comparator 13.
The prior art thus constructed is intended to change r.p.m. of the compressor 6 only with the inverter 7 (while keeping the r.p.m. of the indoor blower high and constant to increase the efficiency of refrigeration cycle in air conditioning), and to compare the temperature from the sensor 11, which detects the temperature Tai of air flowing into the indoor heat exchanger (hereinafter referred to as room temperature), with the temperature preset by the setting unit 12, so that the room temperature is made equal to the preset temperature, thus changing the amount of radiant or absorbed heat through the indoor heat exchanger, thereby producing a comfortable environment in the room. However, those areas in which the heating load during winter is larger than the air cooling load during summer present a problem in that, even with the prior art for controlling the room temperature to bring it to the preset temperature at the starting of heating, it takes time until the occupants of the room start to feel comfortable. They feel rather uncomfortable at the starting of the heating operation. This results from the fact that the prior art has been directed to a system for just sending heat into the room to increase the room temperature without taking into account the effect of air flowing in the room upon thermal comfort and the effect of radiation from walls.
The present invention aims to provide a heat pump air conditioner which can produce a comfortable environment for the occupants of room, particularly those who are directly subjected to blown air, even during a large heating load such as at the start of heating.